From The Last Sovereign Wiki

Melymyn is the fanatical leader of the Mother's Guard, a religious militia in the Elven Kingdoms of Arclent. Since they can mostly bypass political authorities and act on the whole forests, that makes her the most powerful public figure of the forests except the queens.

Although the Mother's Guard is encountered as soon as the first visit in the Elven Kingdoms, Melymyn herself isn't seen until the Council of Gawnfall, which she attends in hope to get concessions from the Church of Ivala.

During the conflict on Thenours, the Mother's Guard prepares massive spells for use in warfare. Melymyn is seen talking directly to the Mother, and approving of her expansionist policies. She then takes part in the negotiations, trying to convince the queens to take a more militant stance.